Slide Slam I9
The effects of white noise and dopamine modulation on novel word learning in healthy young adults.
Marie-Pier McSween1,2, Katie L. McMahon3, Anthony J. Angwin1, Wayne J. Wilson1, Robert J. Barry4, Robert J. Adam2,5, Samuel Armstrong1, David A. Copland1,2; 1School of Health and Rehabilitation Sciences, The University of Queensland, St Lucia, Queensland, Australia, 2The University of Queensland Centre for Clinical Research, The University of Queensland, Herston, Queensland, Australia, 3School of Clinical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia, 4School of Psychology and Brain & Behaviour Research Institute, University of Wollongong, New South Wales, Australia, 5Department of Neurology, Royal Brisbane and Women’s Hospital, Brisbane, Queensland
The administration of the dopamine precursor levodopa and the behavioural manipulation of auditory white noise are both novel approaches that may potentially benefit cognitive function, including new word learning in healthy adults. It has been suggested that white noise benefits non-linguistic learning by engaging a dopaminergic neural network, however this proposed link is yet to be examined with linguistic learning such as new word learning. The aim of this study was to investigate the influence of white noise on new word learning in healthy young adults and examine whether this influence is modulated by changes in dopamine. Forty-nine healthy young adults (mean age= 23.9 ± 3.7; age range 19-33; 35 females, 14 males) participated in this double-blind, placebo-controlled, mixed-groups trial. Participants attended a single session where they completed a baseline word learning task, ingested a single placebo or levodopa capsule (random allocation) and subsequently completed an in-scanner (fMRI) associative novel word learning task. Participants were presented with 40 coloured pictures of aliens, each paired with a 3-word name. All names comprised a novel word followed by two attributes (e.g., floobs wise silent). The 40 aliens were presented in 2 learning blocks of 20 aliens, with all aliens within each block presented 3 times. Each presentation of the 20 aliens was followed by an immediate in-scanner recognition task. Half of the participants were randomly assigned to listen to white noise (set at 70 dB) during the first learning block and the other half during the second learning block. During the in -scanner recognition tasks, participants were asked to select the correct first name for each alien out of 4 choices. Delayed novel word recall and recognition, and attribute recognition were also assessed 25 minutes later. Linear mixed model analyses were performed using SPSS with recall/recognition accuracy as the dependent variables. Fixed factors included group (placebo and levodopa) and noise (silence and white noise). Participants were included as a random factor and baseline word learning ability was included as a covariate. Main effects were followed by Bonferroni-corrected post-hoc tests and a p value <.05 was used to determine significance. No main or interaction effects involving group and noise were found when examining immediate and delayed recognition accuracy data. In contrast, while the analysis of delayed novel word recall revealed no main effect of noise and no group-by-noise interaction, a main effect of group was evident F(1, 93)=6.647; p=.012, reflecting higher recall accuracy in the levodopa group relative to the placebo group. Irrespective of white noise, levodopa benefited delayed novel word recall in healthy young adults. Further analysis using the fMRI data will allow elucidation of the neural mechanisms underpinning the beneficial effects of levodopa on novel word learning.